Osteosarcoma is among the most common malignant bone tumors in human skeletal system. The conventional treatment of osteosarcoma mainly consists of combining neoadjuvant chemotherapy with surgical approach. However, it is crucial to design an artificial implant that possesses excellent biomechanical properties and is capable of sustaining local release of chemotherapeutics. In this study, we envision that the highly efficient combination of gemcitabine (GEM) hydrochloride loaded liposomes with gelatin methacryloyl (GelMA) of in situ photocrosslinkable hydrogel will lead to a multifunctional implant with unique antitumor, mechanical, and biodegradable properties. A sustained controlled release was observed; more specifically, the release of GEM in vitro lasted for 4 days long. Furthermore, its capability in killing MG63 cells was further explored by using the lixivium of GEM-Lip@Gel and GEM-GelMA hydrogel in vitro (composite hydrogel by GEM loaded liposomes blending with GelMA, short for GEM-Lip@Gel), which agreed with the drug release outcome. In addition, these hydrogel showed excellent ability in inhibiting osteosarcoma in vivo by Balb/c mice bearing MG63 cells. Therefore, GEM-loaded lipo-hydrogel certainly has presented itself as a promising strategy for the development of implant in the field of osteosarcoma treatment.

Surgery is the final choice for most patients with intervertebral disc degeneration (IDD). Operation-caused trauma will cause inflammation in the intervertebral disc. Serious inflammation will cause tissue defects and induce tissue degeneration, IDD recurrence and the occurrence of other diseases. Therefore, we proposed a scheme to treat recurrence after discectomy by inhibiting inflammation with an aspirin (ASP)-loaded hydrogel to restore the mechanical stability of the spine and relieve local inflammation. ASP-liposomes (ASP-Lips) were incorporated into a photocrosslinkable gelatin-methacryloyl (GelMA) via mixing. This material can effectively alleviate inflammation by inhibiting the release of high mobility group box 1 (HMGB1) from the nucleus to the cytoplasm. We further assessed the expression of inflammatory cytokines, such as interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α), and degeneration-related factors, such as type II collagen (COL-2), Aggrecan, matrix metallopeptidases-3 (MMP-3), MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) and ADAMTS-5 in rat nucleus pulpous cells. The level of IDD was analyzed through H&E, safranin-O staining and immunohistochemistry in rabbit samples. In vitro, we found that ASP-Lip@GelMA treatment significantly decreased inflammatory cytokines, MMP-3 and -13, and ADAMTS-4 and -5 and up-regulated COL-2 and Aggrecan via the inhibited release of HMGB-1 from the nucleus. In vivo, ASP-Lip@GelMA can effectively inhibit inflammation of local tissue after disc surgery and fill local tissue defects. This composite hydrogel system is a promising way to treat the recurrence of IDD after surgery without persistent complications.

The periosteum plays a vital role in both development and injury healing process of bone. However, few researches have focused on artificial periosteum, which was also limited by the complexity on its construction and biological risks for clinical practice. In order to tackle this issue, inspired by the structural development of periosteum, we put forward a hierarchical micro/nanofibrous bionic periosteum with sustained releasing of VEGF as exogenous vascularized fibrous layer of periosteum to induce endogenous cambium layer in vivo for complete regeneration of periosteal and bone tissue, through collagen self-assembly and micro-sol electrospinning technologies. The VEGF encapsulated in hyaluronan-PLLA core-shell structure was demonstrated to be released in a durable way for angiogenesis in fibrous layer and bone defect area. Meanwhile, the self-assembly of collagen together with electrospun fibers contributed to a hierarchical micro/nanostructure which greatly mimicked the microenvironment of extracellular matrix to provide structural and biochemical cues for cell adhesion, proliferation and differentiation, and lead to the formation of cambium layer which mimicked the in-situ ossification manner as intramembranous ossification. As the motif of this study, the periosteal regeneration was characterized both by osteoblasts and periostin, which represented structural and molecular mechanisms respectively. Furthermore, the periosteal biomaterial proposed here possessed the superior abilities of scar inhibition, angiogenesis, osteogenesis to repair the bone defect in a uniform and rapid manner by inherent periosteal ossific mechanism involved in both intramembranous and endochondral ossification. Thus, the endogenous-exogenous combined bionic periosteum proved to be efficient and versatile in triggering periosteal and bone regeneration and hopefully supply a promising strategy for solving clinical issue.

Chemotherapy and gene therapy are used in clinical practice for the treatment of castration-resistant prostate cancer. However, the poor efficiency of drug delivery and serious systemic side effects remain an obstacle to wider application of these drugs. Herein, we report newly designed PEO-PCL micelles that were self-assembled and modified by spermine ligand, DCL ligand and TAT peptide to carry docetaxel and anti-nucleostemin siRNA.

Three dimension (3D) printed scaffolds have been shown to be superior in promoting tissue repair, but the cell-level specific regulatory network activated by 3D printing scaffolds with different material components to form a symbiosis niche have not been systematically revealed. Here, three typical 3D printed scaffolds, including natural polymer hydrogel (gelatin-methacryloyl, GelMA), synthetic polymer material (polycaprolactone, PCL), and bioceramic (β-tricalcium phosphate, β-TCP), are fabricated to explore the regulating effect of the symbiotic microenvironment during bone healing. Enrichment analysis show that hydrogel promotes tissue regeneration and reconstruction by improving blood vessel generation by enhancing oxygen transport and red blood cell development. The PCL scaffold regulates cell proliferation and differentiation by promoting cellular senescence, cell cycle and deoxyribonucleic acid (DNA) replication pathways, accelerating the process of endochondral ossification, and the formation of callus. The β-TCP scaffold can specifically enhance the expression of osteoclast differentiation and extracellular space pathway genes to promote the differentiation of osteoclasts and promote the process of bone remodeling. In these processes, specific biomaterial properties can be used to guide cell behavior and regulate molecular network in the symbiotic microenvironment to reduce the barriers of regeneration and repair.

Gene therapy is identified as a powerful strategy to overcome the limitations of traditional therapeutics to achieve satisfactory effects. However, various challenges related to the dosage form, delivery method, and, especially, application value, hampered the clinical transition of gene therapy. Here, aiming to regulate the cartilage inflammation and degeneration related abnormal IL-1β mRNA expression in osteoarthritis (OA), the interference oligonucleotides is integrated with the Au nanorods to fabricate the spherical nucleic acids (SNAs), to promote the stability and cell internalization efficiency. Furthermore, the complementary oligonucleotides are grafted onto hyaluronic acid (HA) to obtained DNA-grafted HA (DNAHA) for SNAs delivery by base pairing, resulting in significantly improved injectability and bio-stability of the system. After loading SNAs, the constructed DNAHA-SNAs system (HA-SNAs) performs a reversible NIR-triggered on-demand release of SNAs by photo-thermal induced DNA dehybridization and followed by post-NIR in situ hybridization. The in vitro and in vivo experiments showed that this system down-regulated catabolic proteases and up-regulated anabolic components in cartilage over extended periods of time, to safeguard the chondrocytes against degenerative changes and impede the continual advancement of OA.

Intra-lesional injections of corticosteroids, interferon, and chemotherapeutic drugs are currently the most popular treatments of hypertrophic scar formation. However, these drugs can only be used after HS is formed, and not during the inflammatory phase of wound healing, which regulates the HS forming process.

Infection caused by bacteria is one of the crucial risk factors for tendon adhesion formation. Silver nanoparticles (AgNP)-loaded physical barriers were reported to be effective in anti-infection and anti-adhesion. However, high silver load may lead to kidney and liver damages. This study was designed for Ibuprofen (IBU)-loaded poly(L-lactide) (PLLA) electrospun fibrous membranes containing a low dosage of Ag to evaluate its potential in maintaining suitable anti-infection and good anti-adhesion effects. The in vitro drug release study showed a sustained release of Ag ions and IBU from the membrane. Inferior adherence and proliferation of fibroblasts were found on the Ag4%-IBU4%-loaded PLLA electrospun fibrous membranes in comparison with pure PLLA and 4% Ag-loaded PLLA membranes. In the antibacterial test, all Ag-loaded PLLA electrospun fibrous membranes prevented the adhesion of Staphylococcus aureus and Staphylococcus epidermidis. Taken together, these results demonstrate that Ibuprofen is effective in enhancing the anti-adhesion and anti-proliferation effects of 4% Ag-loaded PLLA fibrous membrane. The medical potential of infection reduction and adhesion prevention of Ag4%-IBU4%-loaded PLLA electrospun fibrous membrane deserves to be further studied.

The balance of redox homeostasis is key to stem cell maintenance and differentiation. However, this balance is disrupted by the overproduced reactive oxygen species (ROS) in pathological conditions, which seriously impair the therapeutic efficacy of stem cells. In the present study, highly dispersed fullerol nanocrystals with enhanced bioreactivity were incorporated into hydrogel microspheres using one-step innovative microfluidic technology to construct fullerol-hydrogel microfluidic spheres (FMSs) for in situ regulating the redox homeostasis of stem cells and promoting refractory bone healing. It was demonstrated that FMSs exhibited excellent antioxidant activity to quench both intracellular and extracellular ROS, sparing stem cells from oxidative stress damage. Furthermore, these could effectively promote the osteogenic differentiation of stem cells with the activation of FoxO1 signaling, indicating the intrinsically osteogenic property of FMSs. By injecting the stem cells-laden FMSs into rat calvarial defects, the formation of new bone was remarkably reinforced, which is a positive synergic effect from modulating the ROS microenvironment and enhancing the osteogenesis of stem cells. Collectively, the antioxidative FMSs, as injectable stem cell carriers, hold enormous promise for refractory bone healing, which can also be expanded to deliver a variety of other cells, targeting diseases that require in situ redox regulation.

Although gradients play an essential role in guiding the function of tissues, achieving synchronous regeneration of gradient tissue injuries remains a challenge. Here, a gradient bimetallic (Cu and Zn) ion-based hydrogel was first constructed via the one-step coordinative crosslinking of sulfhydryl groups with copper and zinc ions for the microstructure reconstruction of the tendon-to-bone insertion. In this bimetallic hydrogel system, zinc and copper ions could not only act as crosslinkers but also provide strong antibacterial effects and induce regenerative capacity in vitro. The capability of hydrogels in simultaneously promoting tenogenesis and osteogenesis was further verified in a rat rotator cuff tear model. It was found that the Cu/Zn gradient layer could induce considerable collagen and fibrocartilage arrangement and ingrowth at the tendon-to-bone interface. Overall, the gradient bimetallic ion-based hydrogel ensures accessibility and provides opportunities to regenerate inhomogeneous tissue with physiological complexity or interface tissue.

Immune response and new tissue formation are important aspects of tissue repair. However, only a single aspect is generally considered in previous biomedical interventions, and the synergistic effect is unclear. Here, a dual-effect coating with immobilized immunomodulatory metal ions (e.g., Zn2+) and osteoinductive growth factors (e.g., BMP-2 peptide) is designed via mussel adhesion-mediated ion coordination and molecular clicking strategy. Compared to the bare TiO2 group, Zn2+ can increase M2 macrophage recruitment by up to 92.5% in vivo and upregulate the expression of M2 cytokine IL-10 by 84.5%; while the dual-effect of Zn2+ and BMP-2 peptide can increase M2 macrophages recruitment by up to 124.7% in vivo and upregulate the expression of M2 cytokine IL-10 by 171%. These benefits eventually significantly enhance bone-implant mechanical fixation (203.3 N) and new bone ingrowth (82.1%) compared to the bare TiO2 (98.6 N and 45.1%, respectively). Taken together, the dual-effect coating can be utilized to synergistically modulate the osteoimmune microenvironment at the bone-implant interface, enhancing bone regeneration for successful implantation.

Lesion positioning therapy optimizes medical treatment by directly targeting lesions. However, strong physical barriers greatly hinder its wide use. Here, the Chinese acupuncture needles (CA-needles) with a screw-thread structure at the tip (ST-needle) and the hydrogel with the function of adhesive metal and loaded drug sustained-release structure are designed, through the minimally invasive and precise positioning of lesions by ST-needles, the dry-wet conversion of hydrogel with absorbing fluids and swelling, and the rotation back of ST-needles, the hydrogel is precisely positioned in the subchondral bone with physical barrier to achieve precise positioning therapy for lesions. In vitro experiments show that the ST-needle penetrates the physical barrier of cartilage and enters the subchondral bone. Simultaneously, the hydrogel transfer efficiency of the ST-needle (73.25%) is significantly higher than that of the CA-needle (29.92%) due to the protective effect of the screw-thread structure. In vivo experiments demonstrate that precise positioning in subchondral bone in osteoarthritis rats with ST-needles effectively inhibits abnormal subchondral bone remodeling, alleviating the degeneration and degradation of cartilage. Therefore, ST-needles achieve lesion positioning therapy through minimally invasive penetration of physical barriers, precisely positioning within lesions, and delivering hydrogel to release drugs.

Nanofat (NF) is a fine emulsion that has been used to treat a variety of diseases given its abundance of bioactive components. However, the biological functions of NF have been limited due to its inability to localize during implantation. In this study, NF was immobilized in microfluidic-generated aldehyde-modified polylactic glycolic acid (PLGA) porous microspheres (PMs) via Schiff base condensation and non-covalent binding in a three-dimensional (3D) porous network (PMs@NF). The PMs effectively enhanced the cartilage-targeted retention efficiency of NF, which also resulted in remarkable lubrication performance, with the friction coefficient being reduced by ∼80%, which was maintained over time. Meanwhile, the 3D penetrating structure of the microspheres stimulated cytokine secretion by the NF-derived stem cells, upregulating the expression of anabolism-related genes and downregulating catabolism, and the expression of inflammation-related and pain-related genes. Injecting PMs@NF into the knee joint cavity of a rat model with destabilization of the medial meniscus (DMM) reduced osteophyte formation and protected the cartilage from degeneration, thereby inhibiting the progression of osteoarthritis and improving animal behavior. In summary, this study developed a multifunctional platform with NF immobilization and super-lubrication, which showed great potential for the minimally invasive treatment of osteoarthritis.

Central nervous system (CNS) injuries, including stroke, traumatic brain injury, and spinal cord injury, are essential causes of death and long-term disability and are difficult to cure, mainly due to the limited neuron regeneration and the glial scar formation. Herein, we apply extracellular vesicles (EVs) secreted by M2 microglia to improve the differentiation of neural stem cells (NSCs) at the injured site, and simultaneously modify them with the injured vascular targeting peptide (DA7R) and the stem cell recruiting factor (SDF-1) on their surface via copper-free click chemistry to recruit NSCs, inducing their neuronal differentiation, and serving as the nanocarriers at the injured site (Dual-EV). Results prove that the Dual-EV could target human umbilical vascular endothelial cells (HUVECs), recruit NSCs, and promote the neuronal differentiation of NSCs in vitro. Furthermore, 10 miRNAs are found to be upregulated in Dual-M2-EVs compared to Dual-M0-EVs via bioinformatic analysis, and further NSC differentiation experiment by flow cytometry reveals that among these miRNAs, miR30b-3p, miR-222-3p, miR-129-5p, and miR-155-5p may exert effect of inducing NSC to differentiate into neurons. In vivo experiments show that Dual-EV nanocarriers achieve improved accumulation in the ischemic area of stroke model mice, potentiate NSCs recruitment, and increase neurogenesis. This work provides new insights for the treatment of neuronal regeneration after CNS injuries as well as endogenous stem cells, and the click chemistry EV/peptide/chemokine and related nanocarriers for improving human health.

Over the last decade, adipose-derived stem cells (ADSCs) have attracted increasing attention in the field of regenerative medicine. ADSCs appear to be the most advantageous cell type for regenerative therapies owing to their easy accessibility, multipotency, and active paracrine activity. This review highlights current challenges in translating ADSC-based therapies into clinical settings and discusses novel strategies to overcome the limitations of ADSCs. To further establish ADSC-based therapies as an emerging platform for regenerative medicine, this review also provides an update on the advancements in this field, including fat grafting, wound healing, bone regeneration, skeletal muscle repair, tendon reconstruction, cartilage regeneration, cardiac repair, and nerve regeneration. ADSC-based therapies are expected to be more tissue-specific and increasingly important in regenerative medicine.

Postmenopausal osteoporosis is one of the most prevalent skeletal disorders in women and is featured by the imbalance between intraosseous vascularization and bone metabolism. In this study, a pH-responsive shell-core structured micro/nano-hydrogel microspheres loaded with polyhedral oligomeric silsesquioxane (POSS) using gas microfluidics and ionic cross-linking technology are developed. This micro/nano-hydrogel microsphere system (PDAP@Alg/Cs) can achieve oral delivery, intragastric protection, intestinal slow/controlled release, active targeting to bone tissue, and thus negatively affecting intraosseous angiogenesis and osteoclastogenesis. According to biodistribution data, PDAP@Alg/Cs can successfully enhance drug intestinal absorption and bioavailability through intestine adhesion and bone targeting after oral administration. In vitro and in vivo experiments reveal that PDAP@Alg/Cs promoted type H vessel formation and inhibited bone resorption, effectively mitigating bone loss by activating HIF-1α/VEGF signaling pathway and promoting heme oxygenase-1 (HO-1) expression. In conclusion, this novel oral micro/nano-hydrogel microsphere system can simultaneously accelerate intraosseous vascularization and decrease bone resorption, offering a brand-new approach to prevent postmenopausal osteoporosis.

Most of the natural extracellular matrix (ECM) is a three-dimensional (3D) network structure of micro/nanofibers for cell adhesion and growth of 3D. Electrospun fibers distinctive mimicked 2D ECM, however, it is impossible to simulate 3D ECM because of longitudinal collapse of continuous micro/nanofibers. Herein, 3D electrospun micro/nano-fibrous sponge was fabricated via electrospinning, homogenization, shaping and thermal crosslinking for 3D tissue regeneration of cells and vascular.

Tendinopathy is a common disorder that causes local dysfunction and reduces quality of life. Recent research has indicated that alterations in the inflammatory microenvironment play a vital role in the pathogenesis of tendinopathy. Herein, injectable methacrylate gelatin (GelMA) microspheres (GM) were fabricated and loaded with heparin-dopamine conjugate (HDC) and hepatocyte growth factor (HGF). GM@HDC@HGF were designed to balance the inflammatory microenvironment by inhibiting oxidative stress and inflammation, thereby regulating extracellular matrix (ECM) metabolism and halting tendon degeneration. Combining growth factors with heparin was expected to improve the encapsulation rate and maintain the long-term efficacy of HGF. In addition, the catechol groups on dopamine have adhesion and antioxidant properties, allowing potential attachment at the injured site, and better function synergized with HGF. GM@HDC@HGF injected in situ in rat Achilles tendinopathy (AT) models significantly down-regulated oxidative stress and inflammation, and ameliorated ECM degradation. In conclusion, the multifunctional platform developed presents a promising alternative for the treatment of tendinopathy.

Peritendinous adhesions, as a major problem in hand surgery, may be due to the proliferation of fibroblasts and excessive collagen synthesis, in which ERK1/2 and SMAD2/3 plays crucial roles. In this study, we hypothesized that the complication progression could be inhibited by down-regulating ERK1/2 and SMAD2/3 phosphorylation of exogenous fibroblasts with celecoxib. Celecoxib was incorporated in poly(l-lactic acid)-polyethylene glycol (PELA) diblock copolymer fibrous membranes via electrospinning. Results of an in vitro drug release study showed celecoxib-loaded membrane had excellent continuous drug release capability. It was found that celecoxib-loaded PELA membranes were not favorable for the rabbit fibroblast and tenocyte adhesion and proliferation. In a rabbit tendon repair model, we first identified ERK1/2 and SMAD2/3 phosphorylation as a critical driver of early adhesion formation progression. Celecoxib released from PELA membrane was found to down-regulate ERK1/2 and SMAD2/3 phosphorylation, leading to reduced collagen I and collagen Ⅲ expression, inflammation reaction, and fibroblast proliferation. Importantly, the celecoxib-loaded PELA membranes successfully prevented tissue adhesion compared with control treatment and unloaded membranes treatment. This approach offers a novel barrier strategy to block tendon adhesion through targeted down-regulating of ERK1/2 and SMAD2/3 phosphorylation directly within peritendinous adhesion tissue.

Hemostasis and repair are two essential processes in wound healing, yet early hemostasis and following vascularization are challenging to address in an integrated manner.